Microelectromechanical systems (MEMS) include micromechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, and/or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. One type of MEMS device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In certain embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by a transparent medium (e.g., an air gap). As described herein in more detail, the position of one plate in relation to the other plate can change the optical interference of light incident on the interferometric modulator. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed.
Conventional interferometric modulator display devices typically implement front-lighting that provides light for viewing images, for example, in the dark. The front-lighting is typically provided by a light strip that surrounds the perimeter of an interferometric modulator display. While such a front-lighting scheme does provide light for viewing images in the dark, there is generally an intrinsic (lighting) uniformity issue as the middle portion of the interferometric modulator display remains darker than the outer edges. As interferometric modulator displays increase in size, this non-uniform effect of light caused by front-lighting increases, which can lead to poor visibility of images in the dark.
Accordingly, what is needed is an improved lighting scheme for an interferometric display device to reduce non-uniformity of light. The present invention addresses such a need.